I'm using minimax for the ai for a tic-tac-toe game im creating. You can customise the size of tic-tac-toe board. I've think ive pretty much implemented it with alpha beta pruning, however I think it mite have a bug or two as it seems to run rather slowly for 4x4 grid size and above... what sort of running times should i be getting considering I have a 2.4Ghz athalon 64...

It is imposible to say ...the speed of you application mostly depends on how well written you code is